7616878bb1
ADR-0007 (rent the trunk) + ADR-0008 (FOB/green-zone doctrine) propagation
into the narrative docs that orient contributors + readers. No code changes.
README:
- Wedge bullet 2: 'one secure auditable boundary' now lists media + local
reflexes + spend + tap + audit (was: trunk termination + media + spend).
Adds the honest caveat that PSTN media inside the boundary is the on-prem
*graduation* (ADR-0007), not a day-one claim.
- 'Is / isn't': 'isn't a TDM/PSTN-hardware PBX — *and not a SIP stack.*'
No first-party SIP (ADR-0007). PSTN reach is rented transport.
- Memory-safety pillar: 'rutster parses no SIP at all' — entire first-party
wire surface is WebRTC/RTP/SRTP + WebSocket tap/ingress, all memory-safe
Rust. The carrier-SIP interop tail lives outside the trust boundary.
- Spearhead step 5: 'Add a real phone number via rented transport' (was:
'Replace WebRTC ingress with a real PSTN trunk call'). Re-aims at the
AI-telephony frontier; no first-party SIP stack.
- References: 0007 supersedes 0003 in the highlighted ADR list.
ARCHITECTURE:
- New 'FOB and the green zone' section after the fused-vertical framing —
names the build-vs-reuse doctrine with the FOB member list + green-zone
member list, and restates memory-safety precisely ('FOB is 100%
memory-safe Rust; the green zone is trusted OSS kept outside the
boundary — not an over-claim that every byte is Rust').
- 'Inside the boundary': 'Carrier trunk — rented transport, not first-party'
replaces 'Trunk SIP termination — Rust-native.' PSTN audio arrives as
a media-leg ingress from a rented CPaaS raw-media fork or an out-of-tree
SBC for on-prem sovereignty.
- Biggest technical risk: 'No longer the SIP stack — because rutster no
longer builds one.' Retires ADR-0003's named schedule risk; redirects
to 'the reflex loop itself' (turn-taking, VAD-driven barge-in, jitter,
pacing) — which is also the differentiator.
PORT_PLAN:
- Design rule 4: 'rent it, don't own it' replaces ADR-0003's 'Rust-native
trunk SIP, no SBC shield.' ADR-0007 restores the rule's original instinct.
- SIP signaling (trunk) row: disposition flipped to 🔌 Rented / out-of-tree.
- Outbound registration row: disposition flipped to 🔌 Rented / out-of-tree
(handled by the rented transport or out-of-tree SBC; rutster parses no SIP).
- Spend/abuse engine row: 'co-located with call origination + the tap inside
the boundary' (was: 'co-located with trunk termination'). rutster mediates
both the provider call-control API and the brain tap — the brain never
holds the wire.
- Spearhead step 5: 'Add a real phone number via rented transport.'
- Open decisions: SIP line updated to 'Re-decided — ADR-0007.'
AGENTS.md:
- ADR list: adds 0007 and 0008 with annotations; marks 0003 as superseded
by 0007.
- Key decisions to respect: prepends the FOB/green-zone doctrine as the
*the* build-vs-reuse rule. 'When in doubt, default to green zone — the
FOB earns its members, it doesn't collect them. This is why the trunk is
rented (ADR-0007) and Valkey reused (ADR-0005), not rebuilt. Don't pull
green-zone plumbing into the core.'
162 lines
9.9 KiB
Markdown
162 lines
9.9 KiB
Markdown
# Rutster
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The open-source engine for building the **AI-era contact center** — self-hostable, AI-native,
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memory-safe Rust. A spiritual successor to Asterisk's *place in the world*, not its protocols
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or its architecture.
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> Not a port of Asterisk. rutster inherits the role Asterisk held — *the self-hostable engine a
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> technical builder uses to stand up a contact center* — and re-aims it at a category AI is
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> actively disrupting, instead of a PBX category UCaaS already ate.
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## Quickstart
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```bash
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# Prereqs: Rust (rustup), libopus dev headers (libopus-dev / opus-devel / brew install opus)
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cargo run
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# listening on http://0.0.0.0:8080
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```
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Open <http://localhost:8080/> → click "Start call" → grant mic → hear yourself echo.
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Full walkthrough + troubleshooting: **[`docs/QUICKSTART.md`](docs/QUICKSTART.md)**.
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> **Status:** Slice 1 (WebRTC media loopback) is the active build target. The workspace is
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> landing task-by-task on the `slice-1-webrtc-loopback` branch. Design:
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> [`docs/superpowers/specs/2026-06-28-slice-1-webrtc-loopback-design.md`](docs/superpowers/specs/2026-06-28-slice-1-webrtc-loopback-design.md).
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> Implementation plan:
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> [`docs/superpowers/plans/2026-06-28-slice-1-webrtc-loopback.md`](docs/superpowers/plans/2026-06-28-slice-1-webrtc-loopback.md).
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## Documentation
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| Doc | For when you want to… |
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| [`docs/QUICKSTART.md`](docs/QUICKSTART.md) | Run it in 5 minutes |
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| [`docs/DEVELOPMENT.md`](docs/DEVELOPMENT.md) | Iterate on the codebase (workspace layout, per-crate testing, dev loop) |
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| [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) | Understand the fused per-call vertical + composable platform + agent tap |
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| [`docs/PORT_PLAN.md`](docs/PORT_PLAN.md) | See every Asterisk subsystem mapped to a disposition (capability checklist, not template) |
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| [`docs/adr/`](docs/adr/) | Load-bearing architecture decisions |
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| [`AGENTS.md`](AGENTS.md) | Project orientation for any agent (human/AI/hybrid) working in the repo |
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| [`CONTRIBUTING.md`](CONTRIBUTING.md) | Trunk-based dev workflow, CI gates, commit style, review checklist |
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| [`LEARNING.md`](LEARNING.md) | Index of "to learn concept X, read file Y" (learner-facing codebase) |
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## Why it exists
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Asterisk won because contact centers were **built on it** (Vicidial, GOautodial, a thousand
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integrator builds) — it never tried to *be* Five9. rutster inherits that position: it is a
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**framework / engine, not a turnkey product**.
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The white space no incumbent fills:
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| Competitor | What they are | rutster's edge |
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| **LiveKit** | Horizontal real-time media infra (Go) | rutster owns the **contact-center domain** (ACD, IVR, queues, recording, CDR, dialer, supervisor) LiveKit will never ship |
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| **Cloud CCaaS** (Five9, Genesys, NICE, Amazon Connect, Twilio Flex) | Proprietary, AI bolted on | Self-hostable, AI-**native**, no per-seat/minute lock-in |
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| **Cloud AI-voice** (Vapi, Retell, Bland) | Cheap managed voice bots | You own your **calls and training data**; it's a *contact center* (escalation, queues), not a single bot |
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| **Dated OSS** (Vicidial, FreePBX) | Self-hostable, Asterisk-era | Modern, AI-native, memory-safe Rust |
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The wedge is a **coherent combination, not a silver bullet**:
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1. **No-GC real-time determinism** — tight turn-taking / barge-in / jitter in a no-GC loop.
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2. **One secure auditable boundary** — media + local reflexes + spend/abuse control + the tap +
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audit in a single memory-safe trust domain. One thing to certify (strongest for PCI / HIPAA / TCPA).
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The carrier trunk is rented (or out-of-tree); bringing PSTN media *inside* the boundary is the
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on-prem **graduation** ([ADR-0007](docs/adr/0007-trunk-rented-transport.md)), not a day-one claim.
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3. **Operational simplicity** — one binary, one bill, one deploy.
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**Honest caveat:** the agent *brain* (STT/LLM/TTS) is necessarily external — audio leaves the box
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to reach it, same as LiveKit. The real-time edge therefore lives in the **local reflexes that don't
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need the brain** (VAD killing TTS the instant the caller speaks, barge-in, jitter, pacing, DTMF),
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not the brain round-trip. The moat is the *whole*.
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## Who it's for
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The modern equivalent of the 2006 Linux-nerd-who-stood-up-Asterisk-for-an-SMB: the
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**CLI/IDE/AI-comfortable self-hosting technical builder** — runs Claude Code in a terminal, lives
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in an editor with an AI pair, versions everything in git, self-hosts on principle. *Not* the no-code
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admin clicking a flow-designer canvas. The builder serves the non-technical operator downstream,
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exactly as integrators did on top of Asterisk.
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## What it is / isn't
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- **Is:** a Rust media core owning the **per-call vertical** (RTP/SRTP media termination + local real-time reflexes + a clean
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audio tap to an external brain + in-boundary spend/abuse control; the carrier trunk is *rented
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transport*, not first-party — [ADR-0007](docs/adr/0007-trunk-rented-transport.md)); a programmable call model exposed as a REST/gRPC API + event stream; WebRTC-first human
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ingress; a library of contact-center capabilities (ACD, IVR, queues, recording, CDR, dialer,
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supervisor) delivered as services around the core.
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- **Isn't:** a TDM/PSTN-hardware PBX — *and not a SIP stack.* No DAHDI, no Sangoma/Digium cards, no
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ISDN/SS7, no IAX2/H.323/SCCP/MGCP/Unistim — and **no first-party SIP**
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([ADR-0007](docs/adr/0007-trunk-rented-transport.md)). PSTN reach is **rented transport** (a CPaaS
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raw-media fork, or an out-of-tree SBC for on-prem media). Inbound SIP *endpoint* registration (desk
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phones) likewise stays out-of-tree — not the browser/SSO UX rutster targets.
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## Core design pillars
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1. **Memory-safe by construction** — Rust everywhere on the hot path; fuzzed sans-IO protocol
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parsers. rutster **parses no SIP at all** ([ADR-0007](docs/adr/0007-trunk-rented-transport.md)): its
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entire first-party wire surface is WebRTC/RTP/SRTP + the WebSocket tap/ingress protocol — all
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memory-safe Rust. The carrier-SIP interop tail lives *outside* the trust boundary (rented transport
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or an out-of-tree SBC), so the buffer-overflow/RCE CVE class is designed out of rutster's own surface.
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2. **Security-as-product** — the single auditable boundary *is* the moat. TLS/SRTP mandatory,
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deny-by-default routing, built-in toll-fraud controls, mTLS gRPC admin (no plaintext AMI), hard
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multi-tenancy. Compliance is a buying criterion, not a row.
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3. **In-boundary spend / abuse control** — spend caps and abuse/pacing control live **inside the
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trust boundary**, co-located with trunk termination. A runaway brain can't exceed pacing or
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spend because it doesn't hold the wire — structurally impossible for a 3-vendor stack.
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4. **Data ownership** — calls and training data never leave the operator's infra. The self-host
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wedge *and* the fuel for the ML self-improvement loop.
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5. **Degradation, deterministic, observable** — no-GC real-time loop; OpenTelemetry traces that
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follow a single call across the boundary; config-as-data, not `.conf` files edited on a box.
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6. **Operational simplicity** — one binary, one bus, one deploy (`compose up`).
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## Layout
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- [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) — the fused per-call vertical + composable
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horizontal platform; the agent tap as the central interface.
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- [`docs/PORT_PLAN.md`](docs/PORT_PLAN.md) — the capability *checklist* (what a telephony system
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must handle), *not* an architecture template. Every Asterisk subsystem mapped to a disposition
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with rationale.
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- [`docs/adr/`](docs/adr/) — decisions. Highlights:
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- [0002](docs/adr/0002-north-star-and-fused-core.md) — north star + fused vertical
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- [0007](docs/adr/0007-trunk-rented-transport.md) — rent the trunk transport; no first-party SIP stack (supersedes [0003](docs/adr/0003-sip-rust-native-trunk.md))
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- [0004](docs/adr/0004-license.md) — GPL-3.0-or-later
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- [0005](docs/adr/0005-event-bus.md) — Valkey (bus + state store)
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- [0006](docs/adr/0006-ingress-posture.md) — WebRTC-first ingress; SIP endpoint deferred
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## Status
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Slice 1 (WebRTC media loopback) implemented; spearhead steps 2–6 pending. The
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[vision revision](docs/superpowers/specs/2026-06-26-vision-revision-design.md)
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and ADRs define the architecture; the
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[slice-1 design](docs/superpowers/specs/2026-06-28-slice-1-webrtc-loopback-design.md)
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documents the active build.
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## First proof (the spearhead)
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The full thin slice, sequenced so each step is its own proof — never a big bang:
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1. **WebRTC media loopback** (terminate RTP/SRTP, echo audio to a browser) — proves the media core
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2. **Add the tap** (route audio to an external echo process and back) — proves the tap interface
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3. **Swap echo for the brain** (ideally a single speech-to-speech API, e.g. OpenAI Realtime, to
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collapse STT+LLM+TTS into one integration) — proves agent integration
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4. **Add barge-in** (VAD-driven playout kill) — proves the reflex
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5. **Add a real phone number via rented transport** (a CPaaS raw-media fork, e.g. Twilio Media
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Streams) — proves a PSTN call reaches the reflex loop, no first-party SIP ([ADR-0007](docs/adr/0007-trunk-rented-transport.md))
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6. **Add the spend cap** (hard-stop at threshold) — proves the boundary
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Steps 1–4 *are* the reflex loop — the hard, most-differentiating part proves itself before trunk
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integration piles on. "I called my Rust box and an AI answered the phone" is the momentum fuel a
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solo multi-year build needs.
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## Capability ladder (the grand vision, incrementally)
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| Rung | Capability | Reuses |
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| 1 | **Self-serve** — AI answers, contains the call | the thin-slice first proof |
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| 2 | **Escalation** — human agent barges in / takes over when AI breaks down | the audiohook/barge primitive |
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| 3 | **Measurement** — containment rate, where/why AI failed | CDR + analytics on calls *you own* |
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| 4 | **Self-improvement** — every takeover → auto-labeled training data → loop | rungs 1–3 compounding |
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## License
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**GPL-3.0-or-later** ([ADR-0004](docs/adr/0004-license.md)). Strong copyleft in the Asterisk lineage,
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modernized one notch. The license is the *floor*, not the moat — the wedge is.
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